So I made Jamil's California Common (minus the chocolate malt) with Wyeast Bavarian Lager yeast (2206). Fermentor samples tasted great, I had about 82% attenuation, so the 'flat' samples were nice and dry. I dry-hopped for 7 days with some extra northern brewers i had lying around, and they did give it a minty/woodsy aroma, I didn't get what I was about to get after it was kegged.

I did a quick force carbonation (high psi, shaking) and transported the kegged beer quite a ways. This was the first beer I've kegged, and while it was good, I noticed an intense (yet sort of pleasant) lemon aroma. The taste was extremely malty, almost sweet up front with a dry (ing) finish.

I suppose that it could have simply been that the beer didn't have enough time to settle out with all the shaking (between my force carbing and the car ride), as we drank it in about 36 hours. Maybe I was just tasting yeast as the beer was a touch cloudy. Also thinking that the profile of this yeast just accentuated the already-malty beer, which I perceived as lemon.

The weirdest thing is, I didn't perceive it when it was flat, but did when it was carbed. Does this sometimes happen when kegging? I've never noticed this much of a difference between flat beer and bottle-conditioned.

It seems that the carbonation will accentuate any smells in your beer; the CO2 coming out of solution will carry the aroma. (At least in my exp; no source.) But, by any chance did you wash your keg with lemon scented dish soap?
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fire.eagleSep 6 '12 at 15:45

This is probably a dumb thing to say, but if it only appeared after kegging, check the keg. I had a porter that I kegged in a corny that I swear I scoured, sanitized, and changed the O-rings on, but it ended up introducing a bizarre, artificial-citrus flavor. My only theory is that somehow the orange soda that the corny had contained at some point had seeped into the metals or something.
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Zac BSep 18 '12 at 21:16

no dish soap, keg was soaked for 10 hours in oxyclean, then double-rinsed and sanitized. Removed all parts as well and submerged in both. It honestly may have been from the dry-hop with Northern Brewers. I have subsequently read that some steams (even Anchor) have a light citrus aroma. Its probably from the hops, particularly the dry hops. I'm going with that.
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PietroOct 3 '12 at 13:55

I have had some wheat beers develop a lemony taste as they age in a keg, they eventually turns sour after a few months.
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corymathewsOct 4 '12 at 13:31

3 Answers
3

This could be a few things, but I think it may be one or all of these:

Bavarian Lager yeast can produce citrusy flavors over time. Some of the Marzens out there that I have found, actually contain a little of citrus. This was probably do more to temp control, but I would fret that much since you were going for a steam beer.

Hops! Depending on the hops used, I know I am probably preaching to the choir, but hops in certain quantities or varitals will give off citrus more than floral or bitter. Seeing that you dry hopped the beer for several days put this on my radar. I have used NB hops with cascade and got a heavy citrus pale ale before.

Kegging, not worried about the force carb, I assumed the keg was well cleaned. The transport is something though. When you say quite a ways, do you mean San Francisco to LA, or like across town? Well the sun cant skunk your beer in a keg, the heat in a car/from the sun can change the flavor. The pressure changes, heat, and sloshing of the beer can do some interesting things. This can reactivate and stress any yeast left, making them give off those esters. Heat affects lupulins chemical structure. This is how we are able to change hop addition times, to change the beers complexity. If this is happening in the keg, this could be the cause of the citrus as well.

Now this lemon can be 1 of the above, a combo, all, or none.

I cant really tell you more from there, but this could also be that each one added a little citrus, and the combination of all of them together just made the lemon pronounced.

Do you remember if it smelled like that before you kegged the beer? My first corny kegs smelled like sweet lemon-lime when I got them from BeverageFactory.com. Apparently it's so common that midwest mentions it in their descriptions:

"Our technicians have also cleaned each keg with a caustic soda rinse
– but even so – the keg may retain a sweet smell similar to a
lemon-lime soft drink."

I think I used either PBW or Oxiclean with hot water and it got it out though, probably PBW since they were new and so dirty. I guess it's possible it was your dry hop, but in my experience citrus/lemon from a hops is very different from this smell.

I suspect a contaminant. Did a Double decoction weissebier on second generation German weissebier yeast and got lazy and let it stay too long in the primary : 3 weeks. Cold crashed and C02 slow carbed. Got a great aroma but lots of lemon taste. Still drinkable but suspect a pH drop related to the unknown bug. I have decided to move the fermenters out of the wood shop since my Big Belgans there get a white haze on top( great taste though) after being in the secondary after a few weeks.